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We present the results of our U BV R c I c photoelectric and CCD photometry of the NLS1 galaxy Ark 564 in 1987–2004. Between late 1997 and 2002, a slight increase in brightness was observed followed by a small but systematic decline until 2004. Ark 564 has a low variability amplitude, within 0.2m in the U BV R c I c bands. The galaxy’s spectral energy distribution at 3600–9000 A is unlike those for Seyfert 1 (Syl) galaxies. A delay of the Ic flux relative to the B flux of about three days was found, which is in agreement with the standard disk model. This delay probably reflects the geometric size of the region that emits the observed continuum.

The E-isomers of α-chlorocinnamonitriles react with hydroxylamine to give a mixture of isomeric aminoisoxazoles, while the Z-isomers yield 3-aryl-2-chloroacrylamide oximes.

The molecular structure of the hydrogen bonded cyclic dimer of dimethylphosphinic acid (Me 2 P(O)OH) 2 was determined by gas-phase electron diffraction (GED) at 433 K. The presence of monomer cannot be determined at this temperature within the error limits for the GED method. Structural analysis was performed with consideration of non-linear kinematic effects at the first-order level of perturbation theory ( h 1). The vibrational characteristics of internuclear distances were calculated from a priori scaled quantum chemical (RHF/6-311G**) force field. The analysis aided by a constraint based on the RHF/6-311G** calculations yielded the following r h 1 -parameters of the C 2 -symmetry dimer configuration: PO 1.497(3); P–O 1.573(4); P–C 1.806(1) and 1.811(1) A; (C–H) av. 1.109(3) A; ∠O–PO 120(1)°. Unlike PO and P–O bonds, whose lengths in the gas phase and in the solid state differ insignificantly, the –O⋯O distance in the gas phase ( r h 1 2.81(4) A) is considerably longer than in the solid state ( r α 2.48(2) A). The latter is in accordance with the conclusion based on the IR spectra that transition from gas to a solid sample leads to strengthening of the H-bonds. Due to its small contribution to the diffraction pattern, the donor O–H bond length ( r h 1 0.99(1) A) was forcedly bound up with the parameters of C–H bonds. With this assumption, the other geometrical parameters characterizing the H-bond fragment have the following r h 1 values: O⋯H 1.84(4) A, ∠–OHO164(6)°, and ∠P–O–H 117(4)°. Conformational flexibility of the non-planar eight-atom ring of the dimer is experimentally verified by absence of any apparent peaks of the f ( r ) curve at the r -region of more than 4.2 A.

Molecular structure of N,N-dimethyldiaziridine was studied by gas-phase electron diffraction and quantum-chemical methods. It is confirmed that the molecule has a trans conformation, but the structural parameters r(endo-C–N) 1.448(2) A, r(exo-C–N) 1.468(2) A, and r(N–N) 1.514(6) A differ substantially from the results of our previous electron diffraction study.

The molecular structure of 6,6′-bis(1,5-diazabicyclo[3.1.0]hexane) was investigated by gas-phase electron diffraction using quantum-chemical calculations. Two conformations were found: boat for bicyclic fragments and anti relative to the exocyclic bond.

The molecular structure of 6-(N,N-dimethylamino)fulvene was studied by gas-phase electron diffraction and quantum-chemical methods (HF/6-31G(d), MP2/3Z, MP2/4Z, density functional theory with the B3LYP/6-31G(d) and PBE/3Z functionals). Pronounced flattening of the nitrogen atom and equalization of the intracyclic C—C bonds were found to be a consequence of the electron delocalization in the molecule.

A new procedure was developed for preparation of ethyl 3-amino-5-arylthiophene-2-carboxylates by the reaction of α-chlorocinnamonitriles and their analogs with ethyl mercaptoacetate for a wide range of substrates. The reaction products form in high yields.

Catalytic olefination of hydrazones of aromatic aldehydes with dibromoacetonitrile affords cinnamonitriles.

A new efficient procedure has been proposed for the synthesis of 3-aryl-5-amino-1H-pyrazoles by reaction of α-chloro-β-arylacrylonitriles with hydrazine hydrate.

The molecular structure of trimethylgermylformate (TMGF) has been determined by electron diffraction in the gas phase. The principal parameters, bond lengths ( r a , A), bond and torsional angles (deg) with the least-squares standard deviations in parentheses, are as follows: GeC, 1.919(21); GeO, 1.820(28); CO, 1.213(76); CO, 1.326(42); CH(methyl), 1.109(80); C6H8, 1.12(fixed); GeOC, 117.6(23); OGeC, 104.9(7); GeCH, 109.8(80); OCO, 125.4(59); CGeC, 113.6(7); OCH, 127(fixed); GeOCO, 81.2(63); CGeOC, 35.5(38); HCGeO, 73.2(52). It is found that the GeOCO fragment of TMGF is not planar, and the HCO plane is close to the perpendicular position with respect to the GeOC plane. This result stands out from the series of previously obtained data for similar molecules and suggests that the conformation of TMGF is controlled mainly by steric effects. The conformation of TMGF from electron diffraction is in agreement with molecular mechanics calculations.

The molecular structure of gaseous Br2Sn(CH2SiMe2)2O was studied by electron diffraction. The six-membered ring has a chair conformation whereas the entire molecule possessesC s symmetry. The existence of a boat conformer cannot be completely excluded. The results of theoretical calculations for a twisted-boat conformation are at variance with the experimental data. Steric strain caused by mutual repulsion of the two axial methyl groups is reduced to the tilt of the Me2Si fragments in opposite directions. This results in an increase (up to 26°C) in the angle formed by the bisector of the CM-Si-CM angle with the CcSiO plane. The main geometrical parameters are as follows:r g (A): Si-O 1.708(20); Si-CM 1.862(20); Si-Cc 1.882(9); Sn-C 2.108(26); Sn-Br 2.456(3); C-H 1.099(30); γα (degr.): C-Sn-C 105(2); Br-Sn-Br 107.9(1.2); Si-O-Si 129.6(3); CM-Si-CM 112; Si-C-H 113 (fixed value in accordance with experiment); Cc-Si-O 107(2); Sn-C-Si 109(2); torsion angles: ϕ(Si-C) 52(2); ϕ(Si-O) 62(1); ϕ(Cc-Sn) 54(1). The average amplitudes were fixed at the values calculated from the force field. Structural parameters of molecules with similar structures were analyzed and compared.

Tris(aziridino)methane has the preferred gauche–gauche–gauche conformation of C3 symmetry unlike the anti–anti–anti conformation of C3v symmetry in the crystal.

A novel method for the preparation of nitriles of α-chlorocinnamic acid from aldehydes and ketones was proposed. Transformation of carbonyl compounds into hydrazones followed by treatment of the reaction mixture with CCl3CN in the presence of copper chloride(i) yields α-chlorocinnamonitriles.

A method for the synthesis of 2,4-diamino-6-arylpyrimidines from guanidine and α-chlorocinnamonitriles was developed. The starting nitriles can be easily prepared by catalytic olefination reaction.

The amount of boat-chair conformation (5–25 %) in equilibrium with the chair-chair has been measured and calculated.

The molecular structure of the title compound has been determined by gas-phase electron diffraction, assuming that the C 2 B 8 unit has the form of a bicapped square antiprism ( D 4d symmetry). The amplitudes of vibration and the shrinkage corrections were calculated from the force field transferred mainly from 1,6-C 2 B 4 H 6 . The molecular parameters ( r g , φ α ) and uncertainties (3σ) are: B-C = 1.602(2), B2-B3 (basal) = 1.850(5), B2-B6 (equatorial) = 1.829(4), B-H = 1.164(14), C-H = 1.14(2) and ∠C-B-H = 117.5(1.8)°. Comparisons are made with structural data for other carboranes studied in the gas phase.

The 3,3-dimethyl-3-silathietane molecule has been investigated by gas-phase electron diffraction analysis with consideration of the vibrational effects. The following geometric parameters were obtained (the distances ra, the angles L~, the errors in the form of 3o in parentheses, for ~ 50): S-C 1.853(4), Si-C m 1.870(5) (m stands for methyl), Si-C r 1.916(3) (r stands for ring), C-H 1.086(3) ~, L(C-Si-C) m = 106.9(7), L(C-Si-C) r = 86.1(3), LSi-C-S = 90.5(5), and LC-S-C = 89.5(4) ~ The fourmembered ring is nonplanar; the angle 9 between the CSiC and CSC planes equals 2 0 . 3 ( 2 0 ) ~

The molecular structure of 2-methyl-l,3,2-dithiaarsolane (I) and l-chloroarsolane (II) has been investigated by means of electron diffraction. Models of molecules with ring symmetry C2 satisfy the experimental data. The following basic geometric parameters have been determined for the molecules (rm structure)~ for I As--C 1.968(20), As S 2.229(2) A; angles SAsS 93.8(0.7), AsSC 100.5(0.8), CCS 111.2(2.2), SAsC 93.3(3.7) ~ For II As-C 1.974(8), As-CI 2.213(4); angles CAsC 88.6(1.3), AsCC 108.1(0.8), CCC 109.6(1.8), CAsCI 97.5(0.7) ~

The structures of the title compounds, diaziridines, (the first to be studied in the gas phase) have been determined by electron diffraction. The following principal structural parameters were obtained with the estimated standard deviations parenthesized: 3-methyldiaziridine, N-C = 1.489(9) A, N-N = 1.444(13) A, C-C = 1.505(16) A, C-H = 1.107(5) A, α =∠ (C-C, NCN) = 61.3° (0.9); 1,2-dimethyldiaziridine, (parameters of the cycle CN 2 were assumed from the previous molecule), N-C (methyl) = 1.445(3) A, C-H = 1.108(9) A, ∠ C-N-Me = 112.0° (0.5), the two methyl groups are in the trans position. Vibrational amplitudes were also determined for all important distances.

It has been established by the methods of x-ray diffraction analysis and electron diffraction analysis and measurements of the dipole moments and the birefringence that in the crystalline and gaseous phases, as well as in solution, N,N-dimethoxyamine has a gauche-gauche conformation, which is stipulated by a stabilizing nOπ-σN-O* orbital interaction. The geometric parameters of the molecule have been determined.

A gas electron diffraction study yielded the following geometrical parameters for hexamethylcyclotrisilazane: r (Si-N) = 1.728 ± 0.004 A, r (Si-C) = 1.871 ± 0.004 A, r (C-H) = 1.124 ± 0.007 A, ∠N-Si-N = 108.4 ± 1.0°, ∠Si-N-Si = 126.8 ± 0.8°, ∠C-Si-C = 108.9 ± 2.3°, ∠H-C-H = 111.6 ± 0.9°. The (SiN) 3 ring was found to be puckered but the deviation from planarity is relatively small. Details of the ring shape could not be determined. The degree of ring puckering in six-membered rings with alternating atoms can be roughly predicted from the bond angles in analogous non-cyclic molecules.

Gaseous μ 4 -oxohexa-μ-nitratotetraberyllium, Be 4 O(NO 3 ) 6 , has been studied by electron diffraction at a temperature of ≈160°C. The intensity data were analysed in terms of a model having T symmetry. The molecular force field was estimated with the aid of a recently developed procedure to provide a satisfactory fit to 29 experimental frequencies and 39 amplitudes within the framework of a 24-parameter force field model. In the final stage of the structural analysis the amplitudes were varied in groups formed on the basis of spectroscopic calculations. The principal geometrical parameters refined to the following values ( r g structure, bond lengths in A, angles in degrees): BeO 1 (O 1 is the central μ 4 -oxygen atom), 1.665(21); BeO, 1.620(8); NO, 1.185(5); NO, 1.298(4); η (the angle of rotation of the NO 3 group about the twofold axis), 25.2(1.8); ∠ONO, 117.0(0.9) (the uncertainties are presented by 2.5 times the standard deviation values, plus a scale error).

The geometrical parameters of tris(trimethylstannyl)amine have been determined by gas-phase electron diffraction. The a structure has been refined using mean amplitude values calculated from the force fields of a number of tin derivatives. The experimental data are consistent with a planar bond configuration at the nitrogen in N(SnMe 3 ) 3 . The final set of geometrical parameters is as follows (average bond distances, r g , in A, angles in degrees): SnC 2.166(5), SnN 2.038(3), CH 1.117(17). NSnC 108.5(1.5), SnCH 112.1(1.6). Mean amplitude values have been varied for those distances which give considerable contributions to scattering. The results obtained fill a gap in the knowledge of structures of Group IV element μ-nitrido derivatives. They confirm the conclusion that lowering of ligand MR n electro-negativity weakens the tendency to deviation from planarity in the central fragment NM 3 . This tendency may be considered as a manifestation of the second-order Jahn-Teller effect.

The structures of (CH3)3Ga·N(CH3)3 and (CH3)3·P(CH3)3 are determined by electron diffraction in the gas phase. The donor—acceptor bonds, Ga—N and GaP, for organogallium complexes are measured and the variation in geometry of the free ligands is discussed.

The structure of the 1,10-C2B8H10 molecule was determined by the electron diffraction method. The following geometric parameters were obtained for the D4d symmetry model: B-C = 1.60(1) A; B-B (basal) = 1.87(1) A; B-B (equatorial) = 1.80(1) A; B-H = 1.17(3) A and the C-B-H angle = 13(5.7)°. These data are in good agreement with the structure of the B10H102− ion or of the less symmetrical 1,6-C2(CH3)2B8H8 isomer.